This invention relates to a conveying system for rigidly interconnected parts in accordance with the preamble of claim 1. The conveying system according to the invention is used particularly in assembly machines for the further processing of semi-product parts. The term rigidly interconnected semi-product parts in this connection denotes parts stamped from a metal strip for further processing as plug pins or sockets. The plug socket parts which have not yet been completed are interconnected by a metal strip which is left between them and which fixes them definitely in respect of their relative position. In the case of plug sockets there are constructions in which the plug-in zone is reinforced by a retaining spring. A retaining spring of this kind is an additional part which is fitted to the as yet uncompleted plug socket in an assembly machine intended for the purpose. For this purpose, the machine is supplied with a strip of plug sockets, the retaining springs being applied to the individual plug sockets at a very high cycle frequency. In these conditions accurate positioning of the plug sockets interconnected by the metal strip is very important so that the retaining spring can be correctly assembled. To this end, holes are stamped in the metal strip and conical centring pins are introduced therein in a conventional conveying system, the pins are moved in the conveying direction with a specific step width, the retaining springs are fitted to the plug sockets and then the conical pins are withdrawn to engage in the next hole situated further back, in order to advance the strip with the plug sockets one step. The movement of the conical pin for the stepwise introduction of the plug sockets into the machine tool is a multi-stage relatively complex process, which limits the maximum cycle frequency of the plug socket processing operation. Also, this conveying system is relatively complicated, maintenance-intensive and trouble-prone due to the number of moving parts which also comprise retaining means which hold the metal strip fast while the conical pins are withdrawn.
The object of this invention is so to improve a conveying system according to the preamble that a higher working cycle frequency can be obtained with simpler means with, at the same time, reduced maintenance outlay and reduced liability to defects.
This problem is solved in accordance with the claim. The sub-claims indicate features of preferred embodiments of the invention.
The idea underlying the present invention is that reliable continuous pressing of the parts, which are rigidly interconnected via a metal strip, against a stop, will ensure adequately accurate positioning of the semi-product parts in an assembly machine so that complicated retention by means of conical pins engaging in holes stamped in the metal strip can be dispensed with. Instead it is sufficient to ensure conveyance of the semi-products interconnected by the metal strip by means of a suitably selected air flow in the conveying direction.